Bluetooth Core Specification Version 5.2 released

Feature Overview (1/3)

Enhanced Attribute Protocol (eATT)
An improved version of the Attribute protocol (ATT), called the Enhanced Attribute protocol (EATT), has been introduced along with some associated improvements to the Generic Attribute Profile (GATT)

EATT supports concurrent transactions, allows the interleaving of L2CAP packets relating to ATT packets from different applications, and allows the ATT Maximum Transmission Unit (MTU) to be changed during a connection. Collectively, these changes can provide an improved user experience on devices where there are multiple applications using the Bluetooth Low Energy (LE) stack at the same time, through reducing instances where one application’s use of the stack temporarily blocks that of another. This can reduce the end- to- end latency of one or more of the applications and improve the user’s experience of responsiveness.

In support of EATT, a new L2CAP mode has been defined. The new mode is called the L2CAP Enhanced Credit Based Flow Control Mode. This mode provides flow control and so allows applications to regard the protocol as reliable. EATT has security advantages over unenhanced ATT as it may only be used over an encrypted connection.